3D/2D Core-Shell CsPbBr3 Microcrystals for Stable X-Ray Detection and Imaging

Although metal halide perovskite (MHP) materials are promising candidates for direct X-ray detection, the surface and internal defects of perovskite polycrystalline thick films lead to severe noise current and poor device stability. Herein, a phenylethylammonium (PEA+) cladding layer was integrated with 3D CsPbBr3 grains, forming 3D/2D core-shell CsPbBr3 perovskite microcrystals. The PEA+, acting as the A-site cation, is able to passivate the surface defects, while the forming 2D perovskite cladding layer inhibits ion migration within CsPbBr3 grains. The blade-coated polycrystalline 3D/2D core-shell CsPbBr3 perovskite thick film exhibits a reduced trap density from 4.32 x 1010 cm(-3) to 4.26 x 109 cm(-3) compared to conventional CsPbBr3 film, with ion migration activation energy increasing from 123 meV to 210 meV. Consequently, the obtained perovskite X-ray detector exhibits a high sensitivity of 29,460 mu C Gy(-1) air cm(-2) and a low detection limit of 84 nGyairs(-1) (50 keV X-ray photon energy), and the detector maintains long-term operational stability with a dark current drift as low as 4.12 x 10(-5) nA mm(-1) s(-1) V-1. Furthermore, we integrated the 3D/2D core-shell polycrystalline CsPbBr3 with a TFT chip (64 x 64 array) and successfully obtained a clear and high-contrast X-ray image of a mouse's paw exhibiting a spatial resolution of 2.5 lp mm(-1).